襄阳市鱼梁洲东线沉管对接端止水墙爆破拆除

Blasting Demolition of Water Stop Wall at Butt End of Immersed Tube in Yuliangzhou East Line of Xiangyang City

沉管对接端止水墙采用机械拆除困难大,采用爆破拆除更为经济高效,然而在距重要结构近且施工技术要求高等情况下采用爆破拆除仍较困难。结合襄阳鱼梁洲东线沉管隧道对接端止水墙爆破拆除实例,介绍了在水深大、壁厚薄且施工作业面狭窄、距被保护建筑物近以及存在一级水保生物等复杂条件下的止水墙爆破拆除施工作业技术。两道止水墙爆破拆除前均采用地质钻在宽度为1.2 m,水下最大深度超过18 m的止水墙顶布设炮孔。东汊止水墙按照设计炸药单耗1.28 kg/m 3进行爆破,达到了预期拆除效果,且与爆源相邻的地连墙永久支护最大峰值振速为8.16 cm/s,离爆源较近的首节待浮运沉管最大峰值振速为3.7 cm/s,水击波最大超压峰值为0.786 MPa,均未造成影响。在总结东汊爆破并考虑东津止水墙实际情况的基础上优化了东津的爆破方案,设计炸药单耗由1.33 kg/m 3调整为1.02~1.33 kg/m 3,不仅达到了预期的拆除效果,爆破振动和水击波也进一步减弱,地连墙永久支护最大峰值振速为7.49 cm/s,离爆源最近的暗埋段主体最大峰值振速为5.03 cm/s,水击波最大超压峰值为0.592 MPa,且均未造成影响。

It is difficult to demolish the water stop wall at the butt end of immersed tube by machinery,and it is more economical and efficient to demolish it by blasting.However,it is still difficult to demolish it by blasting when it is close to the important structure and requires high construction technology.Combined with the example of blasting demolition of water stop wall at the butt end of immersed tube tunnel on Yuliangzhou east line in Xiangyang,the paper introduces the blasting demolition construction technology of water stop wall under the complex conditions of large water depth,thin wall,narrow construction working face,close to the protected buildings and the existence of first-class soil and water conservation organisms.Before the blasting demolition of the two water stop walls,the geological drill is used to arrange the blast holes on the top of the water stop wall with the a width of 1.2 m and the maximum underwater depth of more than 18 m.According to the design explosive consumption of 1.28 kg/m 3,the East branch water stop wall was demolished,and the expected demolition effect was achieved.The maximum peak vibration velocity of the permanent support of diaphragm wall adjacent to the explosion source was 8.16 cm/s,the maximum peak vibration velocity of the first section of immersed tube to be floated near the explosion source was 3.7 cm/s,and the maximum overpressure peak of water hammer wave was 0.786 MPa.Based on the summary of Dongcha blasting and considering the actual situation of Dongjin water stop wall,the blasting scheme of Dongjin is optimized.The designed explosive consumption is adjusted from 1.33 kg/m 3 to 1.02~1.33 g/m 3,which not only the expected demolition effect is achieved,but also the blasting vibration and water shock wave are further weakened.The maximum peak vibration velocity of the permanent support of the diaphragm wall is 7.49 cm/s,The maximum peak velocity of the buried section closest to the explosion source is 5.03 cm/s,and the maximum overpressure peak value of water hammer wave is 0.592 MPa,all of which have no influence.